This disclosure relates generally to x-ray imaging systems, and more particularly to techniques for correcting the effects of electromagnetic interference (EMI) on image data acquired with such x-ray imaging systems.
A number of x-ray imaging systems of various designs are known and are presently in use. Such systems generally are based upon generation of x-rays that are directed toward a subject of interest. The x-rays traverse the subject and impact a film or a digital detector. Increasingly, such x-ray imaging systems use digital circuitry for detecting the x-rays, which are attenuated, scattered or absorbed by the intervening structures of the subject. In medical imaging contexts, for example, such systems may be used to visualize the internal structures, tissues and organs of a subject for the purpose of screening or diagnosing patient ailments. In other contexts, parts, structures, baggage, parcels, and other subjects may be imaged to assess their contents, structural integrity or other purposes.
In the field of diagnostic imaging, digital x-ray detectors are gradually replacing film cassettes. Digital x-ray detectors generally provide better image quality and improved processing time, image storage and image transfer over previously known x-ray film techniques. However, digital x-ray detectors are susceptible to EMI. The EMI may create artifacts in the x-ray images.
Sources of EMI may include, for example, various electrical and electronic equipment and systems used in the vicinity of the digital x-ray detectors. Temporally and spatially changing electromagnetic fields can induce phantom signals in the digital x-ray detector that show up as image artifacts in an acquired image. Depending upon the phase, frequency and amplitude of the EMI, artifacts in the reconstructed images may generally take the form of darker and lighter parallel rows superimposed on the basic image. Such artifacts are not only distracting, but may impair effective use of the images, such as for diagnosis in a medical context. In particular, such artifacts may make small or more detailed features that would otherwise be visible in the images, difficult to detect. These image artifacts can degrade the overall image quality of a digital x-ray imaging system. Although shielding can be used to attenuate the amplitude of the electromagnetic radiation, this shielding will also attenuate the x-ray radiation and degrade the overall image quality of the x-ray imaging system.
Therefore, there is a need for a digital x-ray imaging system having a digital x-ray detector with reduced sensitivity to EMI that produces high quality images with no artifacts.